I'm guessing you are trying to brute force a login form, sometimes with hydra cli you have to play with it editing number of threads, etc. Here is a good tutorial which explains all the GET/POST methods as well as using hydra on brute forcing and launching a dictionary attack.
Also you need to supply good password / bad password condition which are called tokens like
^PASS^ in the URL where they are to be replaced by the usernames and passwords under test. The second is done by hydra by string matching against the returned page. You can either test for a failure condition, such as "Bad password", or a success condition, such as "logged in". If you don't supply the conditions how does hydra know what
username:password combination is the correct one? You need to let hydra know what it means to login successfully and unsuccessfully, each website is different like "Bad Password" "Login Incorrect "Please Try Again".
Here's a very simple command line example:
hydra 127.0.0.1 http-form-get '/login.php?username=^USER^&password=^PASS^:Bad password'
PS: Also sometimes due to high number of threads the page doesn't have time to load giving you false positives always try to decrease thread count.